Underfloor wiring duct system

Application filed March 13, 1929. Serial No. 346,598.

This invention relates to underfloor ducts for electrical conductors and has particular reference to buildings in which the flooring and ceiling supported by steel girders either B resting on masonry walls or forming part of ^v a steel structural building. In modern steel building construction, a concrete floor covering overlies the steel floor girders and underfloor ducts are often embedded therein and 10 supported thereby. By placing the girders nearer together, it has been possible to materially reduce the thickness of the floor covering and thus reduce the overall thickness of floor and girder, but in doing this, the cov15 ering becomes too thin to permit of ducts of practicable size being embedded therein. In the present invention the necessity of embedding the ducts in the concrete floor covering is obviated by making the ducts an ex20 tension or part of the girders themselves, so that instead of the floor covering supporting the ducts, the floor or ceiling rests directly on the ducts and is supported thereby.. I incorporate these steel ducts more or less intimate25 ly with the floor girders or with enough of them to give the desired distribution. In this way the duct may be made of any capacity without encroaching on the floor section, and it may not require separate laying 30 as the placing of the girder may simultaneously establish the duct in the right place and in the proper alignment.

Other details and advantages will be described with reference to the accompanying ³⁵ drawings illustrating various embodiments of the invention, and in which

Figure 1 is a plan view of the floor girders of a building.

Figure 2 is a vertical section on the line ⁴⁰ 2—2 of Figure 1.

Figure 3 is a perspective view of one form of girder.

Figure 4 is a plan view partially in section ₄₅ showing the junction of two girders.

Figure 5 is a transverse section of a girder of the form shown in Figure 3, in line 5 5 of Figure 1, with the superposed flooring.

Figure 6 is a similar view of a transverse 59 girder on linq 6—6 of Figure 1.

Figures 7 and 8 are plan views of certain arrangements of girders and ducts.

Figure 9 is a vertical section on line 9—9 of Figure 8 showing an assembly of transverse truss girders on longitudinal I-beams. _S5

Figure 10 is a vertical section through the floor of a building showing a part of a longitudinal girder in side elevation.

Figures 11 and 12 are modified forms that my improved girder may take. go

Figure 13 is a perspective view showing a girder with a duct in both the upper and lower flange members.

Referring first to Figure 1, there is shownat 1 longitudinal girders supported on pillars gs 2. Upon these girders rest the ends of transverse girders 3 in the well-known manner of constructing steel buildings. As shown in Figure 3, the upper stress member of the girder has its flanges 4 rolled in L or Σ shape 70 to form a longitudinal channel in the top of the beam. The flange 4 may have lip flanges 5 formed thereon providing at the upper inside edges of the channel, recesses 6 which may form seats for a longitudinal cover plate 75 7 (see Figures 1 and 5). The transverse beams 3 may be of the same general construction as the longitudinal beams 1, although they may be of smaller dimensions (compare Figure 6 with Figure ,5). Where the trans- go verse beams meet the longitudinal beams, I provide orifices 8 in the vertical sides of the flanges 4 to furnish communication between the channels of the longitudinal girder and of the transverse girders. Not all of the 35 transverse girders need be provided with ducts. As shown in Figure 1, two girders 9 having no ducts may be spaced between the duct girders. As is customary, the steel floor girders form only a framework upon 90 which a flooring of some kind is supported, this flooring generally being of concrete, such as shown at 10, Figures 2, 5 and 6. At the junctions of the longitudinal and transverse channel girders, outlet boxes 11 are supported 95 on the girders and rise to a level with the floor surface where they may have a proper outlet cover 12. These outlet boxes may fit within the recesses 6 between the ends of the cover plates 7 (Figure 1), thus forming a 100

1,815,447 substantial steel to steel construction. The girders may take the form of a truss 13 as shown in Figure 9 where the longitudinal girder is of the usual I-beam form and the ⁵ transverse girders are of the open truss-work form with a channel duct rolled integral with their upper stress member forming a box-like stress member of great strength. Here a modified form of construction is shown in ¹⁰ which a duct 15 is laid along the longitudinal I-beam on top of its top flange, the duct in this case being manufactured separate from the girder and only associated with it in the assembly of the building. When so assem¹⁵ bled, however, it forms practically an extension of the girder for supporting the floor covering and is itself firmly supported throughout its length. Such a construction is shown in Figure 11 in cross-section with ²⁰ the supplemental duct 15 riveted to the top flanges of the I-beam, but I regard it within the scope of my invention to have the duct 15 merely laid on the I-beaiii as shown in Figure 12. Whether made integral with the ²⁸ girder or built upon the girder, the duct must be made strong enough to support the floor and any loading thereof. In certain parts of the floor as shown in Figure 7, a connection 14 in the form of a tube may be used to ³⁰ connect the outlet boxes in place of supplement duct 15.

In Figure 8 is shown a box-like duct 16 which is enclosed at top and communicates at its ends with covered outlet boxes 11.

³⁸ It will be observed with reference to Figure 13 of the drawings that applicant may provide the wire receiving ducts in both the upper and lower stress members of the girders. It is obvious that when using the girders ⁴⁰ with ducts in their lower stress members, access to the intercommunicating girder ducts can be conveniently provided through the enclosing ceiling covering which extends over the ducts, whether above or below or both, in ⁴⁵ the same manner as above described with specific reference to the floor coverings. The expressions employed in the claims such as “enclosing covering” or “floor” or “floor-like covering” are intended to cover a floor, a ceil⁵⁰ ing or other building wall or partition, supported above or below the girder ducts having the defined characteristics of the invention.

It will be seen that the duct walls become ⁵⁵ really an extension of the girder and that the weight of the floor is transferred to the girder through them. As the ducts do not encroach on the space allotted to the floor covering, they may be made as large as desired. The ⁶⁰ ducts are laid in place in the ordinary process of erecting the steel and do not require many if any separate operations.